feat: add session image retrieval endpoint

Add HTTP endpoint to retrieve saved session images by session ID.
Images are saved during car_fueling progression stage.

- Add GET /session-image/{session_id} endpoint
- Search images directory for files matching session ID pattern
- Return most recent image if multiple exist
- Proper error handling (404 for not found, 500 for errors)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app.py

@@ -302,6 +302,63 @@ async def get_camera_image(camera_id: str):
         raise HTTPException(status_code=500, detail=f"Internal server error: {str(e)}")
 
 
+@app.get("/session-image/{session_id}")
+async def get_session_image(session_id: int):
+    """
+    HTTP endpoint to retrieve the saved session image by session ID.
+
+    Args:
+        session_id: The session ID to retrieve the image for
+
+    Returns:
+        JPEG image as binary response
+
+    Raises:
+        HTTPException: 404 if no image found for the session
+        HTTPException: 500 if reading image fails
+    """
+    try:
+        from pathlib import Path
+        import glob
+
+        # Images directory
+        images_dir = Path("images")
+
+        if not images_dir.exists():
+            logger.warning(f"Images directory does not exist")
+            raise HTTPException(
+                status_code=404,
+                detail=f"No images directory found"
+            )
+
+        # Search for files matching session ID pattern: {session_id}_*
+        pattern = str(images_dir / f"{session_id}_*.jpg")
+        matching_files = glob.glob(pattern)
+
+        if not matching_files:
+            logger.warning(f"No image found for session {session_id}")
+            raise HTTPException(
+                status_code=404,
+                detail=f"No image found for session {session_id}"
+            )
+
+        # Get the most recent file if multiple exist
+        most_recent_file = max(matching_files, key=os.path.getmtime)
+        logger.info(f"Found session image for session {session_id}: {most_recent_file}")
+
+        # Read the image file
+        image_data = open(most_recent_file, 'rb').read()
+
+        # Return image as binary response
+        return Response(content=image_data, media_type="image/jpeg")
+
+    except HTTPException:
+        raise
+    except Exception as e:
+        logger.error(f"Error retrieving session image for session {session_id}: {str(e)}", exc_info=True)
+        raise HTTPException(status_code=500, detail=f"Internal server error: {str(e)}")
+
+
 @app.get("/health")
 async def health_check():
     """Health check endpoint for monitoring."""